The skin actively resists bacterial infection by its excellent barrier properties and by initiating both cognate and innate immune responses. Human keratinocytes are activated by bacterial endotoxin, LPS, which is a major cell wall component of gram negative bacteria. However, little is known about keratinocyte LPS receptor expression and function. Therefore, this application will test the following hypotheses: The human keratinocytes are capable of expressing functional CDI4 and TLR2/4 LPS receptors. Activation of the CDI4 and TLR2/4 by bacterial derived LPS initiates a series of innate antimicrobial inflammatory responses. Innate inflammatory activities initiated by CDI4 and TLR4 activation by bacterial derived LPS include the production of a number of proinflammatory peptides.